1. Field of the Invention
This invention relates generally to securement of loads and in particular to securement of loads for transport by railcar, and is more particularly directed toward a system for restraining loads in box cars or other transportation vehicles by use of a web strap net and ratchets.
2. Description of Related Art
Loads being transported generally require some type of restraint system in order to prevent damage to both the load and the transportation vehicle. Loads on rail cars need to be restrained from shifting under the various loads imposed by draft, buff, and rocking of the car.
For particular types of loads, such as large rolls or coils of sheet material, or palletized loads, tensioning mechanisms using straps and anchors are advantageous. When cargoes contained in boxes or bags, and arranged on pallets or slip-sheets, are loaded into railcars, some form of cargo restraint is required. One presently known form of load restraint is a movable bulkhead or “door” that can be placed in selected positions along the length of a box car. This bulkhead is held in place by locking pins inserted into floor tracks and ceiling tracks. Adjustment of bulkhead position is facilitated by rollers on a ceiling carriage that engages a ceiling rail or track.
This bulkhead approach has become less popular in recent years due to high maintenance. A bulkhead unit will frequently fail because the unit ceases to roll well, or fails to lock properly. There is also a safety concern, since bulkheads can disengage from the top track and fall, causing injury or death to workers, and damage to railcars and cargoes.
A form of bulkhead restraint system implemented with web strapping and ratchets has been tried on railcars and highway trailers. In this prior art system, the web connects to a side wall via a wall anchor and hook, extends outwardly at an angle of about 90 degrees to a point on the opposite wall of the car or trailer. This portion of the web is connected to the opposite wall via similar wall anchors and hooks. To provide tension in this “bulkhead web,” ratchets are provided on the netting itself.
This system has a number of disadvantages, among which are an inherent “cross-car” load distribution that has a tendency to pull car walls in. In addition, the bulkhead web is not easily positioned or adjusted to prevent undesired load shift. Accordingly, a need arises for a load restraining device that is dependable and safe in operation, as well as being economical to install and relatively maintenance-free. The load restraining device should be capable of providing appropriate load tension to prevent load shift, as well as keeping the load centered in the car or trailer to eliminate the need for so-called “center-void” fillers.